Study On Water Demand For Natural Service Of Second Songhua River With Physical Habitat Model And Water Flow Process

Due to factors such as population and climate, our country has been in a state of severe water shortages. In recent years, with rapid growth of the social and economic water resources requirement, more pressure was imposed on the supply and configuration of water resources, domestic water and industrial water requirement increased and water ecological environment suffered serious interference, leading to dry rivers and damaged ecosystem. However, along with the increasing of water pollution control and water environment regulation, rivers and lakes water quality deterioration trend were basically under control, with the national grade Ⅰ～Ⅲ river length ratio reached to 68.6%,2013, bad V kind of long river water occupied 14.9%, higher and lower than those in 2012 by 0.6% and 0.8%, respectively. Under this background, the water ecology gradually become China’s water conservancy practice and science research hot spot and also the difficult point. Since the 1980s, our country started to do systemic study on ecological water demand, but the research methods lack ecology basis, and still on an exploring stage in the aspect of combining with aquatic habitats to evaluate the application of river ecological water requirement.Based on the Songhua river basin water ecological status and the necessity of research on the ecological water demand of river, this dissertation takes the second Songhua river as the study area, treating the coordinated development of watershed ecology and environment as a whole, considering the characteristics of river channel cross-section, hydrological processes and the biological behaviors of target species, integrated with the comprehensive habitat simulation method and flow process of pulse, proposed the ecological water demand of the important river partition in fish spawning period to provide fundamental support for adaptive management of river ecological restoration. The main works done are as follows:(1) Build the ecosystem hydrological models of the second main stream of Songhua riverAccording to the different hydrological characteristics of two main river section,249 measured river cross sections were selected, on the basis of model PHABSIM, to build the second Songhua river ecological and hydrological models, and the hydraulic elements in different characteristics discharge were estimated, so that the water level and velocity distribution under different characteristics discharges were simulated.(2) Identify habitat distribution for different fishes in their spawning periodsTake the Jarraud fish and Aojiang who produce viscous eggs and floating eggs, respectively, as double indicator species, the indicator species spawning period habitat suitability curve were drew out, and by PHABSIM to simulate the distribution and change of the habitat of the typical fishes in their spawning periods, and then determined the main spawning location.(3) Determine the range of ecological flow based on habitat areaCombined with the location of the main spawning grounds, the range of ecological flow for the second Songhua River is determined during fish spawning period based on the change of effective habitat area for each section under different flow. Considering the restriction of runoff during fish spawning period, the range of minimum ecological flow for floating egg generated fish species is 1000 m3/s-1200 m3/s, while the suitable ecological flow for viscous egg generated fish species is 800 m3/s.(4) Ecological water requiring process based on flow pulse simulationThe method for calculating ecological water requiring process based on flow pulse simulation is proposed, combined with the concept of river ecological flow. And this method is used to calculate the ecological water requiring process of the second Songhua River during fish spawning period. According to the results simulated by daily runoff process of Songhuajiang hydrological station from 2006-2010, the flow pulse process and parameter values for April to August are determined based on the spawning period for main fish species. Then the ecological water requiring process is determined based on the relationship between life habit of fish species and parameter values.According to the results of simulated ecological flow and ecological water requiring process, the minimum ecological flow for floating egg generated fish species is, while the suitable ecological flow for viscous egg generated fish species is. Both two methods show clear biological significance and ecological value, and the final simulation results are the same.